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MG Midget and Sprite Technical - New harness Frogeye

I do need to rewire and looking at the wiring diagram, the Frogeye is pretty straightforward. I know I can buy a ready made harness and I know a company like AutoSparks will add additional wires. However because a few things on my car are not standard, or the positions are not strictly correct, I am just thinking about the benefits of making up my own loom.

This raises a few fairly basic questions for which some guidance would be appreciated.

What is the best "wrap" for the loom? There seem to be a whole range of options including self amalgamating tape, shrink sleeve etc. I am not too concerned that this isn't the correct "period" material - I just want something which is easy to apply neatly.

Is is normal practice in a loom to run all the earths back to a central point or generally rely on local earthing on say the attachment screws? In my experience, local earthing like that gets unreliable.

There are a number of points where a single feed wire splits to feed say, left and right lights. In the old days that would I guess have been done with a bullet connector. Nowadays, and assuming that such joints could be contained within the overwrap of the loom, is there a better way (soldered junctions with shrink sleeve perhaps?)

And finally, for the moment, the car has been converted from positive to negative earth. Apart from the battery connection itself and the connection to the coil, are any other conncetions reversed from those shown on the wiring diagram (which is positive earth, of course)?

Graeme Williams

Hey Graeme,

I have been doing a lot of refurbishment of my loom in the past few weeks. Tidying up bodges, a couple of modifications etc. I might one day make up a new loom to replace the current, slightly delapadated one.

I found this place has a great selection (no relation or interest in this company!):

Perhaps a suitably sized one of these would work for junctions in the loom?

They are great for straight butt connections.

M Le Chevalier

Years ago I made up a loom for a frog. it was fun at the time but getting all the wires of the correct colour/amperage was difficult. I used the non adhesive tape.

I did not use a central earth point but retained the original local earth and did not have any problems. The car was used for production and classic trials and regularly got very wet and muddy.

The bullet connector joints I suspect were just there to facilitate the assembly on the production line. I soldered connections where possible.

I have to say when I restored my current frog 4 years ago, I used an Autosparkes one with suitable modifications. it has been completely reliable.
Bob Beaumont

I'm colour blind, so I would wire it all in one colour!
(first part IS true; not so sure about the second)
Graeme Williams

Hello Graeme.

If it helps, I've been using this stuff for years for looming and protecting wires (and hoses).
Polyethylene spiral wrap.

Bit of a gobfull - just copy/paste to your browser search box.

No tools required, just a bit of patience to wind it round the wiring bundle.
Advantages are: easy to remove if you need to. Wires can break out of the loom any where you want. Cheap. Protects against chafe. Not constricting, unlike shrink wrap or tape. Allows the wiring to cool as the spiral doesn't completely cover it.

On the earthing question - I don't know about Frogs but my 1500 has separate earths, at least from high current components like lights, going to earth poles (bolts) which are then connected to the battery negative pole. A quick peep at the wiring diagram just now and I can't immediately see anything that doesn't have a wired earth.
The better and more direct earthing you can achieve the better it'll work, because the voltage drops will be minimised. Personally I'd choose that approach over local chassis earthing anytime. On Lifeboats for example, not only is everything wired to earth points, but all the earth points are bonded (wired) together to eliminate any PDs that could lead to galvanic corrosion.

Hope this helps you, and good luck.
RS Hughes

Hi Graeme

Autosparks sell standard and modified Frogeye looms (e.g. Negative earth and alternator conversions) as well as offering a rebraiding service. Probably cheaper and easier than making your own loom from scratch.

You can buy the wire, connectors and wrap from Vehicle Wiring Products.

M Wood

BTW the heatshrink insulted terminals that M Le Chevalier pointed you towards are very good. He's quite right, I've used them many times, most recently this morning on my mate's trailer socket wiring.

However you do need a proper ratchet type crimping tool to assure a good connection and it's not cheap. Also you need a heatshrinking gun, a hairdrier won't do it. It takes a fair bit of heat to to shrink the sleeve and melt the glue. (Tip: when you see the glue coming out out of the back of the joint stop and let it cool. That's it cooked)!

Have you thought about providing relays for the headlights? MGOC spares scheme sells a kit and I used it on my 1500. The current load at the column switch is down to milliamps (meaning it will last until long after I am dead) and my headlights are superbright compared to their previous glimmer due to the reduction in voltage drop.

Cheers. R.
RS Hughes

Hi R

THe headlamps do have a relay added by a po. Probably the same bloke who decided only one fuse was needed and who wired the radiator fan so it rotated in the wrong direction against the flow of the mech fan and the moving car. It actually got warmer if I put the fan on!

Graeme Williams

Hahaa! Graeme be fair - it's one fuse more than MG used! And he might have wanted to use the fan as propellor to go 0.01 mph faster!
Best of luck with the Frog nervous system. I quite enjoy a bit of cable-strangling myself.

RS Hughes

THere are actually two fuses. The second one is blown, and live both ends (which is interesting from two aspects)!
But for all that, it all works. I just make good use of the battery isolator when I'm not around.
Graeme Williams

This thread was discussed between 03/02/2015 and 04/02/2015

MG Midget and Sprite Technical index

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